#include <iostream>
using namespace std;
int main()
{
	int i;
	double n,s=2;
	double step=s,total=0;
	cin>>n;
	for (i=0;total<n;i++)
	{
		total = total + step;
		step = step * 0.98;
	}
	cout<<i<<endl;
	return 0;
}
